CONCERNING  THE  OCCURRENCE  OF 
FREE  PENTOSES  IN  PLANTS 


liY 


L.  W.  VAN  RYN 


THESIS 


FOR  THE 


degree:  of  bachelor  of  science 

IN 

CHEMICAL  ENGINEERING 


COLLEGE  OE  LIBERAL  ARTS  AND  SCIENCES 


UNIVERSITY  OF  ILLINOIS 


1922 


UNIVERSITY  OF  ILLINOIS 


liar  OR 


192 i 


THIS  IS  TO  CERTIFY  THAT  THE  THESIS  PREPARED  UNDER  MY  SUPERVISION  BY 


.lx*—’ EL— ‘ Yan-Rvi 


ENTiTLED___£L<ini2.ejming._tJie__Qcjiuairfinc-e__Qf— Fxefi.-P^nJiojs.es.-i 1 


IS  APPROVED  BY  ME  AS  FULFILLING  THIS  PART  OF  THE  REQUIREMENTS  FOR  THE 
degree  of JBa.clifiLQ.r__Qf__Sfi.i£ii£Le__irL_Ciiej2iiii£ — — -- 


HEAD  OF  DEPARTMENT  OF 


. 


table  of  contents 


Page 

Aclmowledgement 

Introduction  — — — ---  1 

Experimental  5 

Experimental  Lata — 8 

Summary 


10 


- 


ACKNOWLEDGEMENT 


The  author  wishes  to  thanh 
Dr.  Duane  T.  Englis  for  his  many 

invaluable  suggestions,  and  for  his 

interest  and  ready  willingness  to 

help  in  the  work. 


Digitized  by  the  Internet  Archive 
in  2015 


https://archive.org/details/concerningoccureOOrynl 


CONCERNING-  THE  OCCURRENCE  OE  EREE  PENTOSES  IN  PLANTS 

By:  1.  W.  van  Ryn,  under  the 

direction  of  Ur.  Uuane  T. 

Englis,  Department  of 
Chemistry,  University  of 
Illinois. 


INTRODUCTION 


The  sugars  occurring  in  plants  are  nearly  all  of  Ihe  five 
and  six  carbon  atom  class,  pentoses  and  hexoses.  Although 
both  are  found  widely  in  the  combined  state  as  polysaccharides 
such  as  starch,  cellulose,  xylan  and  araban,  only  the  hexoses 
occur  extensively  in  the  free  state.  The  presence  of  mono- 
saccharide pentoses  has  been  but  recently  established.  If  the 
sugars  are  considered  to  be  formed  by  a successive  condensation 
of  formaldehyde  it  would  seem  reasonable  to  expect  that  pentoses 
should  also  be  found  free. 

However,  there  is  the  possibility  that  pentoses  may  be  p 
produced  as  waste  products  in  a down  grade  process  in  the  plant 
since  according  to  Armstrong1 2  they  are  present  as  skeletal 
and  not  as  food  products  and  are  therefore  not  fermentable  by 

ordinary  enzymes. 

2 

Spochfr  has  brought  out  the  theory  of  the  formation  of 
pentoses  from  such  substances  as  glucuronic  acid.  He  states 
that  in  the  disaccharides  and  poly-saccharides  the  CEgQH 
group  is  the  first  to  be  effected  and  that  such  a reaction 
results  in  a primary  formation  of  glucuronic  acid,  CH:0( CHOEy^GOOH. 
A veiy  general  property  of  saccharides  of  this  character  is  the 
splitting  off  of  COg  from  the  carboxyl  group  and  so  glucuronic 
acid  would  form  1 - xylose. 

t 

1.  Camagie  Institute  Pub.  287  - 1919 

2.  The  Carbohydrate  Economy  of  Cacti.  1919 


. 


* 


-2- 


Such  an  oxidation  would  permit  the  production  of  pentoses 
from  hexoses  while  the  latter  were  still  in  certain  poly  sac- 
charide forms,  i.e.  one  in  which  the  primary  alcohol  group 
was  exposed  and  consequently  the  pentose  would  not  be  liberated 
except  on  hydrolysis  of  the  stable  polysaccharide  and  would 
perhaps  not  be  found  abundantly  in  the  plant  sap. 

Also  if  pentoses  are  derived  from  a direct  oxidation  of 
hexoses,  d - glucose  would  yield  d -arabinose  and  d - galact- 

ose^ould  yield  d - xylose.  ^ 

Qff  //  Ofr 


CoH- 


H- 


0 

H b 

(■ 

FT 

< 

d - glucose  d - ar&binose 

1$  is  a striking  fact,  however,  that  in  nature  d - glucose 
is  almost  always  found  with  1 - xylose  and  that  d - galactose 
is  usually  associated  with  1 - arabinose.  Also  tjae  pent- 
oses sugars  thus  formed  are  of  the  1 - and  not  of  the  d - 
series.  The  fact  and  the  isolation  of  glucuronic  acid  by 
Spoch£  seems  to  substantiate  his  theory  of  the  method  of  form- 
ation. 

Davis  and  Sawyer  have  given  evidence  of  pentoses  in  the 
free  state.  They btfsed  their  conclusions  on  the  fact  that  a non- 
fermenting,  reducing  sugar  was  obtained  from  a plant  extraction 
after  a fermentation  with  yeast  and  that  by  running  the  regular 


■ 


, 


* 


-3- 


ICobliA=TollenT  s determination  a greater  ppt.  was  obtained  than 
could  be  accounted  for  as  due  to  hexoses  alone. 

Moreover,  for  the  purpose  of  neutralizing  any  organic 
acids  that  were  present,  they  added  ammonium  hydroxide  (sp.  gr. 
.0.88)  to  the  alcoholic  extract  in  a proportion  of  1 $ by 
volume.  This  treatment  would  tend  to  throw  some  doublt  as  to 
the  conclusion  of  their  results.  The  isomerizing  effect  of 
weak  alkalies  upon  sugars  is  v/ell  recongnized  to  day.  Also,  it 
seemed  possible  that  the  introduction  of  air  to  lessen  bumping 
during  concentration  might  have  caused  an  increased  oxidation 
of  the  sugars  and  increased  pentose  formation. 

The  evidence  is  not  conclusive  because  Nef  has  indicated  th 
that  a great  number  of  products  may  be  formed  and  the  nature 
of  the  products  depends  on  the  temperature  and  concentration. 

Hale  has  sought  to  verify  or  disprove  the  conclusion  of 
Davis  and  Sawyer  by  an  investigation  of  the  effect  of  their 
precess  of  extraction  with  a mixture  of  pure  hexose  sugars. 

As  a result  of  his  work,  he  concludes  that  although 
considerable  quantities  of  apparent  pentoses  produced  from  the 
hexose  sugars  are  indicated  by  both  methods  used  by  Davis  and 
Sawyer,  the  amount  is  insufficient  to  account  for  the  total 
quantities  reported  by  them  in  their  plant  extract  solutions. 

Since  in  plant  extracts,  phosphates  and  many  other  mineral 
salts  may  be  present  it  seemed  desirable  to  study ' further 
Davis’s  process  of  extraction  in  the  presence  of  certain  amounts 
of  these  salts  in  order  to  determine  their  influence  on  apparent 


, 


' 


-4- 

pentose  production. 

In  prliminary  work  this  writer  was  unable  to  duplicate 
exactly  some  of  the  resits  of  Hale  so  it  appeared  advisable  to 
repeat  his  work  in  some  detail  and  then  proceed  to  the  study 
of  the  effect  of  phosphates  on  the  process  of  extraction# 

It  has  been  stated  by  E.J.  Wittzman"^  that  di^sodium 
phophate  catalyzes  the  quantitative  oxidation  of  glucose  to  00^ 
by  hydrogen  peroxide.  Previous  work  by  L0b  states  that  in 
a salt-free  solution,  hydrogen  peroxide  produces  only  a vanishing- 
ly small  amount  of  oxidative  glycolysis  and  that  this  is 
markedly  increased  by  raising  the  hydroxyl  ion  concentration 
and  that  the  phosphate  ions  accellerate  the  glycolysis  by  the 
OH  ions. 


l.  Jour.  Bio.  Chem.  (Wittzeman) 


- 


v: 


EAPEBIMMTAL 

Preparation  of  Solutions: 

Twenty  grams  of  pure  sucrose  was  dissolved  in  220  c.c 
of  distilled  water,  100  c.c,  of  this  solution  was  inverted  with 
invertase  and  made  up  to  220  c.c.  This  was  called  solution  A. 
The  invertase  was  prepared  according  to  Sherman  and  was 
dialyzed  to  remove  any  sugars.  Another  100  c.c.  portion  of  the 
original  solution  was  diluted  to  220  c.c.  This  was  called 
solution  B.  Now,  by  using  100  c.c  of  each  A and  B a solution 
could  be  obtained  which  would  have  sucrose  and  invert  sugar 
in  about  equal  proportions  and  a total  sugar  content  slightly 
less  than  ten  grams. 

Extraction  Process: 

Experiment  I : Into  750  c.c.  of  boiling  alcohol  50  clc. 

of  each  A and  B was  measured,  then  5 c.c.  of  ammonia  (sp.  gr. 

0. 90)  was  added.  This  solution  was  refluxed  on  the  water 
bath  in  a Pyrex  flask  for  eighteen  hours.  After  refuxing  the 
solution  was  concentrated  fo  about  150  c.c.  under  diminished 
pressure.  During  concentration  air  from  a capillary  tube 
was  allowed  to  bubble  slowly  through  the  solution  to  lessen 
bumping.  The  150  c.c  residue  was  diluted  with  water  until  its 
volume  reached  500  c.c.  The  solution  was  then  cleared  with 
basic  lead  acetate,  filtered  and  washed  to  about  1000  c.c. 
Excess  lead  was  removed  with,  sodium  carbonate  and  the  precip- 

1.  J.  Am.  Ghem.  Soc.  36,  1566  (1914) 


-6- 

itate  filtered  off  and  washed  until  the  volume  was  two  liters. 

Another  solution  prepared  by  diluting  100  c.c.  of  each 
A and  E to  two  liters  with  water  was  used  as  a blank  for  comp- 
arison with  the  refluxed  solution. 

Experiment  II 

The  above  experiment  was  then  aarried  out  with  the  omission 
of  any  introdpiction  of  air  to  lessen  bumping  as  it  was  thought 
possible  that  this  might  have  caused  an  increased  oxidation  of 
the  sugars  and  an  increase  in  pentoses. 

Experiment  III 

This  experiment  was  the  same  as  Experiment  I except  that 
the  refluxing  for  eighteen  hours  was  ommitted. 

Determination  of  Pentoses  by  Distillation 

After  deleading  with  sodium  carbonate  50  c.c.  portions 
of  this  filtrate  were  distilled  with  E01  according  to  the 
regular  Kobler- To liens  Method  of  analysis  and  the  precipitate 
resulting  from  the  coupling  with  phloroglucin  was  weighed. 

In  carring  out  this  distillation  the  rate  of  distillation 
was  maintained  as  near  to  30  c.c  eveiy  10  minutes  since  accord- 
ing to  Van  Hears t and  Olivier'1’  except  in  the  case  of  1 - arbin- 
ose,  more  complete  distillation  of  the  furfural  is  obtained 
?/hen  the  time  is  short.  Continued  boiling  with  HOI  tending  to 

1.  Chem.  Vocekblad  11,  918  (1914) 


< 


, 


-7- 


de compose  the  furfural. 

Exp  esriment  IV 

Ten  percent  ferric  chloride  was  added  to  50  c.c  portions  of 
the  filtered  extraction  III.  The  regular  Kohler- Tollens 
test  was  run  on  it  and  pentose  calculated. 

Experiment  V 

The  sodium  phosphate  and  hydrogen  peroixide  were  added 
according  to  Watze/mann,  to  Extract  III  and  the  pentose 
determined. 

Experiment  VI 

The  Kobler- To liens  determination  was  made  on  a half  gram 
sample  of  pure  non-reducing  Sucrose  and  the  results  compared 
with  those  obtained  after  the  additcSn  of  the  phosphate  and 
the  hydrogen  peroxide  to  pure  sucrose. 


. 


■ 


-8- 


EXPER IlIER TAL  RESULTS 

The  results  of  the  experiments  explained  above  are 
recorded  here: 


Blank:  a 

b 

Exp.  I:  a 
b 

Expe  II  a 

b 

Exp. Ill  a 

b 


APPARENT  PENTOSES 

Phloroglueid 

— .0027 

— -----  - — - .0028 

— .0054 

— .0052 

.0054 

.0052 

- .0012 

— . .0020 


Pentose 

.0080 

.0081 

.0107 

.0105 

.0107 

.0105 

.0065 

.0072 


Exp.  IV  a — -• - — .0048  .0101 

b ----- — — .0039  .0093 

Exp.  V a — — — — .0090  .0141 

b — .0090  .0141 


Exp.  VI  (pure  sucrose) 

a -- .0068  .0120 

b .0063  .0116 

a'  — — — — .0101  .0153 

b' .0108  .0161 

After  the  addition  of  the  phloroglucinol  care  was  taken 

not  to  allow  the  solution  to  stand  longer  than  over  night 

before  filtering  it  for  it  was  observed  that  after  the  filtrate 


-9- 


had  stood  for  some  time  an  additional  precipitate  came  down. 

The  duplication  of  Hales  work  gave  results  of  smaller 
magnitude  than  he  obtained  but  of  the  same  order. 

The  addition  of  the  ferric  chloride  shows  a very  marked 
increase  in  pentose  formed. 

The  addition  of  the  di- sodium  phosphate  and  hydrogen 
peroxide  shows  a very  great  increase  in  pentose  formed — 
practically  double  the  amount  formed  without. 


.ir  : . 


. 

' 


-10- 


SUMMABY 


1,  Pentoses  are  ):nown  to  be  found  in  the 
free  state.  This  is  evidenced  by  the  facts 
that  after  fermentation  of  hexoses  with 
brewers  yeast  a non- fermentable  residue  remained 
and  more  phloroglucid  was  obtained  than  could 

be  accounted  for  as  due  to  hexoses  along.  The 
extraction  of  the  hexoses  involved  refluxing  with 
ammonical  alcohol  and  concentration. 

2.  It  is  shown  in  this  paper  that  such  an 
extraction  gives  considerable  quantities  of 
apparent  pentoses  and  further  that  the  presence 
of  certain  salts  produces  a large  increase  of 
apparent  pentoses. 


